1. Field of the Invention
This invention relates generally to apparatus for continuously measuring and/or monitoring the width of a slab being discharged from a slab caster. More particularly, this invention relates to a new and improved device or apparatus for in-process monitoring of the width of such a slab, hot or cold, which will permit continuous or intermittent measurement to achieve closer process controls to improve yield and product quality, and which can readily be attached to a conventional roller table upon which such workpieces are normally conveyed during processing.
2. Description of the Prior Art
In state of the art continuous casting of steel slabs, adjustable mold sides are normally provided which can be set and adjusted to provide an opening that will theoretically produce the desired slab cross-sectional dimensions. While the slab thickness is normally adjusted by altering the width of the narrow faced mold sides; i.e., utilizing different mold sides having differing widths, the slab width in most casters can be changed in-process by adjusting the positions of the narrow faced mold sides. Specifically, the two narrow faced mold sides are adjustably mounted between the two wide faced mold sides so that the distance between them can be adjusted to vary the resulting slab width.
It is known, however, that there are a number of different factors involved in continuous slab casting, independent of the caster mold setting, that can cause shrinkage of the slab or otherwise influence the dimensional parameters of the cast slab such as mold wear, heat transfer conditions, and mold distortion due to thermal and mechanical strain, as well as down-stream secondary cooling conditions. It is further known that these factors can and do change and vary during a given casting operation. As a result, it is very difficult to accurately predict the discharge dimensions of any continuously cast slab.
Since it is intended that the slabs will be further rolled into semi-finished and finished steel products whereby the thickness will be greatly reduced, the exact thickness dimension of the continuous cast slab is not particularly critical. The width of the slab, however, is not normally reduced in the subsequent rolling operations, at least for the production of flat rolled products such as strip and sheet products. It is critical therefore, that in such rolling operations the starting slabs have a given minimum starting width as necessary to achieve the desired end width in the finished product, and the slab width is, therefore, a more critical dimension to achieve.
In order to assure that the continuous cast slabs will have a defined minimum width, it has been normally necessary to adjust the mold sides to produce a somewhat excessive slab width to thereby accommodate for any large degree of shrinkage that may occur, but yet may not. As a result of this practice, there may be considerable yield losses when slabs are produced and sold at widths in excess of the ordered width.
In current continuous slab casters, a measuring device is normally provided at a horizontal roller table over which the cast slabs pass for the purpose of periodically measuring the edge-to-edge width of the cast slab to assure specifications are being met. Such measuring devices are normally mounted on movable, position controlled, sideguards which can be activated to move against the two side surfaces of the slab and provide a reading of the slab width at the area of measurement. At best, such measuring devices provide a measure of the maximum width within the slab length contacted by the sideguards. In addition, such prior art width measuring devices may require that the slab movement on the roller table be stopped in order to make the measurement, and an undesired passage of time occurs while the measuring device is activated to close on the side surfaces of the slab to make the measurement and thereafter to be withdrawn to permit further processing. Accordingly, such prior art measuring devices provide only a periodic measurement of the slab width as a statistical check. While some of the more recently developed measuring devices are designed to provide a continuous measurement of a slab in motion, the mechanical mechanisms to effect such a continuous measurement normally comprise a rather complicated linkage to bias a pair of measuring wheels against the sides of the slab in motion, and specific modifications of the roller table to permit their installation. Accordingly, such prior art devices leave something to be desired in simplicity and ease of installation.